UL 796 CRD-2016 UL Standard for Safety Printed-Wiring Boards - Section Paragraph Reference 26 2 2 Subject Printed-Wiring Boards (Edition 11 May 31 2016).pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared by UL LLC. It is normative for the applicable ULProduct Certification Program(

2、s); however, it is currently not part of the UL Standard(s) referencedbelow.Product Category (CCN): ZPMV2Standard Number: UL 796Standard Title: Standard for Safety for Printed-Wiring BoardsEdition Date: May 31, 2016Edition Number: 11Section / Paragraph Reference: 26.2.2Subject: Printed-Wiring Boards

3、DECISION:26.2.2 Peel a uniform width of the conductor A uniform width of the conductor is to be peeled from thesample surface for a distance of at least 6.4 mm (0.25 inch) at a uniform rate of approximately 300305mm/min (12 inches/min) (or approximately 6.4 mm or 0.25 inch in 1.25 seconds). The angl

4、e between theprinted conductor and the base material is to be maintained at not less than 85 degrees during the test,and the force required to separate the conductor from the laminate is to be measured. Three forcedeterminations, as described above, are to be made on each conductor width, as describ

5、ed above, oneach sample.Exception: As an alternative to using three force determinations, one force determination can be madeon each conductor described in 26.2.1 on each sample tested by peeling a uniform width conductor fromthe sample surface for a distance of at least 19 mm (0.75 inch).This is ge

6、nerated text for figtxt.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULRATIONALE FOR DECISION:When performing bond strength testing, the initiation of the pull causes the force to over shoot the actualstrength of the conductor as shown in Fig

7、ure 26.1. It has been determined that more consistent bondstrength data is obtained by using one force determination with a longer distance peel instead of usingthree shorter peel determinations. The longer distance peel allows the conductor pull force to stabilize. Ifthe conductor is pulled for the

8、 same distance as required in total during three force determinations, thetotal required peel distance does not change. The use of one force determination is being proposed as analternate method to the three force determination to allow for the use of either method depending on thesample configurati

9、on. Other minor modifications to the peel descriptive paragraph were made in order toharmonize the wording in UL 796 and UL 796F.Copyright 2016 UL LLCUL LLC, in performing its functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decis

10、ions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of UL LLC. in practically applying therequirements of the standard. They do not represent formal interpretations of the standard underAmerican National Standards Institute (ANSI

11、) processes. UL LLC shall not be responsible to anyone forthe use of or reliance upon Certification Requirement Decisions by anyone. UL LLC shall not incur anyobligation or liability for damages, including consequential damages, arising out of or in connection withthe use or reliance upon Certificat

12、ion Requirement Decisions. The electronic version of the CertificationRequirement Decision is the current version and previously printed copies may be outdated.Figure 26.1Determining average bond strength from the average forceSTANDARD NUMBER: UL 796 -2-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FUR

13、THER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThis document is published as a service to ULs certification customersSTANDARD NUMBER: UL 796 -3-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSTANDARD NUMBER: UL 796 -4-No Text on This Page